Influence of silk-fibroin fibers on mechanical and biological properties of PDLLA salt-leached scaffolds

A major tissue engineering approach is to use scaffolds designed as temporary extracellular matrix (ECM) supports for cells. In this study a new construct was prepared combining a porous scaffold of Poly D, L-Lactic Acid (PDLLA) with silk-fibroin fibers. Constructs comprising PDLLA and PDLLA plus fibers were compared for their properties as well as their abilities to support relevant in vivo cell populations.Morphological characteristics were assessed using Scanning Electron Microscopy and Micro Computed Tomography, elastic moduli were measured using a mechanical testing apparatus. Human Mesenchymal Stem Cells (hMSC) and Human Umbilical Vein Endothelial Cells were seeded onto the scaffolds and maintained for four weeks in vitro. Our findings suggest that the porosity of the novel scaffold is comparable to the PDLLA salt-leached scaffold, despite its greater stiffness. However, support of cell populations varies considerably. In particular it seems that endothelial cell localization is strongly associated with fiber presence yet, in the absence of fibers, an early osteogenic differentiation of hMSCs is seen in the scaffolds, leading to enhanced ECM production.This study shows the influence of silk fibroin fibers on mechanical and biological properties of PDLLA salt leached scaffold. The concept of designing composite scaffolds to integrate beneficial properties of different structures and materials seems a promising avenue to facilitate appropriate biological interaction.